Fuel for gas turbine

ABSTRACT

A fuel for use in gas turbines which is a heavy distillate corresponding to the 300* - 450*C. fraction from the first distillation of a crude oil having a flow point no greater than 48*C, a viscosity at 100*C. no greater than 10cs, a flashpoint greater than 75*C. and generally between 150*-250*C., and a low sulfur, metal and water content.

United States Patent [191 Tintori [4 1 Feb. 19, 1974 FUEL FOR GAS TURBINE [75] Inventor: Julio Tintori, St. Cloud, France [30] Foreign Application Priority Data Nov. 14, 1969 France 69.39325 [52] US. Cl. 208/15 [51] Int. Cl C] 1/00 [58] Field of Search 208/ [56] References Cited UNITED STATES PATENTS 2,664,388 12/1953 Winterhalter 208/15 FOREIGN PATENTS OR APPLICATIONS 907,783 10/1962 Great Britain 208/15 OTHER PUBLICATIONS Popovich et al., Fuels and Lubricants, 1959, Wiley & Sons, New York, page 153.

Primary Examiner1-lerbert Levine Attorney, Agent, or FirmBrowdy & Neimark [5 7 ABSTRACT A fuel for use in gas turbines which is a heavy distillate corresponding to the 300 450C. fraction from the first distillation of a crude oil having a flow point no greater than 48C, a viscosity at C. no greater than 1005, a flashpoint greater than 75C. and gener ally between -250C., and a low sulfur, metal and water content.

2 Claims, No Drawings FUEL FOR GAS TURBINE The present invention relates to a fuel having determined characteristics, for use in a gas turbine; and more particularly to the use of this fuel in industrial combustion turbines, for the production of electrical energy or simultaneously of electrical energy and vapor.

It has been known for several years that combustion engines of the turbine type can operate with gaseous fuels such as natural gas, or liquid fuels such as naphtha, kerosene, domestic fuel, etc. the boiling point of which at atmospheric pressure is lower than 360C or at most equal to it.

There has now been discovered a new fuel for combustion turbines, which, aside from its especially favorable economical aspects, possesses natural physical characteristics suitable for this use without it being necessary to correct or to transform it by artificial means such as the use of additives or various treatments such as purification, strong desulfuration, etc.

The new fuel according to the present invention, which may be classified in the group of heavy fuels, is characterized by its volatility, that is by its distillation curve defined by its initial boiling point of 300C; its final boiling point of 450C.; and by the points 380C; 50% 400C, 90% 410C. and 95% 420C. Being a heavy distillate it may be made up of the liquid fraction of a straight-run of a crude oil first distillation, recovered at a point situated below gas-oils extraction; it may also be obtained by distillation under reduced pressure, of distillation residues at atmospheric pressure of a crude oil at a drawing off zone intermediary between gas-oil and bitumen.

Such a fraction has a whole series of characteristics which renders it particularly interesting for the specified use.

The flowing point of a liquid fuel has a great importance for its use; this point must be found below the minimal temperature at which fuel is stored, transferred and used. In utilization conditions according to the invention, it is less than 48C. or at most equal to it.

Moreover, the carbon content according to the Conradson test, which permits forecasting of the repercussions of fuel heavy elements on motor behavior and measures the more or less pronounced trend of this fuel to be cokified, is of a value lower than 0.4 percent.

in order to ensure the most favorable conditions for an excellent combustion, fuel pulverization must be the finest possible. This is of course dependent upon the fluid. The most favorable cinematic viscosity for fuel used, according to the present invention, measured at the temperature of 100C. .is less than 10 centistokes.

Flash point, defining the temperature at which the new fuel takes fire with flame contact, ranges from a temperature greater than 75C. and generally between 150 and 250C.

The sulfur content of the new fuel, for its use in combustion turbines, must be such that corrosion and atmospheric pollution hazards are poor. Practically, applicant has established that sulfur limits could go up to 2 percent (of fuel weight). It should be noted that as a practical matter the sulfur content of this new combustible is clearly lower than that value.

In the same way, the metal content of the new fuel, such as vanadium, calcium, sodium, potassium and lead must be low in order to avoid corrosion attack of the turbine blades. Vanadium, for example, is oxidized by combustion to vanadium pentoxide, then transformed into ashes which adhere to hot metal surfaces thereby corroding their protective layer.

Thus, it has been established that if the contents of those various metals do not exceed an upper limit, the corroding action is very poor. Practically the fuel according to the present invention does not contain generally more than 2 parts per million of vanadium, 2 parts per million of sodium, 5 parts per million of sodium and potassium together, 5 parts per million of lead and IOparts prrnilli'on of calcium. 7 1

Finally, the water content of the new fuel is at most equal to 0.15 percent while sediment content is practically non-existent.

industrially, the new fuel according to this invention, may be used in industrial stations of energy production, using gas turbines of known type, coupled with usual alternators or any other rotative machines. A generating-vapor boiler or any exchanger with water circulation may be associated to combustion turbines, in order to produce simultaneously electric energy and steam under pressure, using the calories of the exhausting gases.

EXAMPLE Viscosity C. 8 centistokes Conradson Carbon 02% Density 50C. 0.888

Flash point 216C.

% ashes traces Sulfur 1.44%

Moisture 100 parts per million (p.p.m.) Vanadium 0.16 p.p.m.

Lead 0.14 p.p.m.

Sodium 0.1 p.p.m.

Potassium lower than 0.1 p.p.m. Calcium 0.1 p.p.m.

Each turbo-alternator was made up of:

a. a combustion turbine of known type composed of a l6-stage compressor rotating at the speed of 5,100 t/mn, with a combustion system and with a 2-stage expansion turbine.

b. an alternator of also known type, having a power of 20,000 kw, under a voltage of 5.5 kw and a frequency of 50 hz.

Above the turbine and interdependent with the turbo-altemator group was a boiler which collected exhaust gases, the temperature of which was 500C, while the rate of produced vapor was 50 t/h under the pressures of.28 bars and 8 bars. i

The emitted fumes were clear, thus showing the excellent combustion of the heaviest fractions of the fuel. ln the same way, several dismantling examinations have not revealed the presence of carbon deposits in the turbines and combustion chambers.

The metal and sulfur contents, well situated within the precited limits, were low enough to avoid the corrosion of turbines and heat exchangers.

It will be obvious to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention. is not to be considered limited to what is described in the specification.

What is claimed is:

1. Fuel for gas turbines, consisting essentially of a heavy distillate boiling from 300-450C. with percent boiling at 380 or less, 50 percent boiling at 400C. or less, 90 percent boiling at 410C. or less and percent boiling at 420C. or less., from the first distillation of crude oil, drawn off at a point of the column situated below gas-oils recovery,'or from the distillation under reduced pressure of a residue of raw petroleum distillation at atmospheric pressure at a point in the column situated below gas-oils recovery, said fuel having a flow point no greater than 48C., a viscosity at C. no greater than 10 centistokes, a flash-point greater than 75C., a sulfur content no greater than 2 percent, and containing no more than 2 parts per million of vanadium, 2 parts per million of sodium 5 parts per million of sodium and potassium together, 5 parts per million of lead, and 10 parts per million of calcium; and a water content no greater than 0.15%.

2. A fuel according to claim 1 wherein said flashpoint is between about l50-250C. 

2. A fuel according to claim 1 wherein said flash-point is between about 150*-250*C. 